TigerBill's DrumBeat Community Forums for Free Expert Advice on Drums and Percussion.

Hi Rapp,

For my first prototype of the three color chromatic keyboard, I worked over a Mallet Kat. This was an older Kat from 15 years ago, but I'm sure the new ones are similar under the pads. If you lift the pads off, you find a sandwhich of three layers of clear plastic. For each pad, on the inner layer of plastic, are printed two combs in metalic ink, much like the ink on a printed circuit board. The fingers of the two combs are interlaced, one finger from each comb fitting between two fingers of the opposite comb, but never touching. Then, metal ink from each pair of combs under each pad runs to a central point where a ribbon of plastic and ink "wires" passes into the box below and is connected to computer chips. When you strike a pad, the impact effects the interlaced comb fingers so that a signal can detect the impact. (There are no piezos in the Kat, it's adifferent system). I was able to peel up the entire palstic sandwhich of twelve notes on a Kat module and cut apart the notes and rearrange them in a chromatic way, and then cobble back the connections to the central ribbon using conductive paint and wires. I then glued the rubber pads back over the notes and painted them three colors. It worked for a few weeks, long enough for me to know the idea was great, but then one of my connections failed and I abandoned it.
As for you rebuilding a Kat by cutting the detectors shorter, I'd be affraid of making such subtantial changes to the combs; I don't know how that would effect the whole detection circuit (change of impedance, etc.) I also don't think the manufacturer will be able to alter the way they make Mallet Kat pads for you; it is a printed manufactured sandwhich and a one-off change would be hard to do. However, they may have smaller single pads available from another type of drum instrument. Another approach you might consider is to use real metal bars with piezo's from K&K. These can produce analoge vibes sound or can go through K&K's midi module to produce midi signals. Then you just have to solve the physical problem of aranging the bars in a chromatic sequence. You could do this by building your own vibes frame and making support pins that zig and zag the the cord in the right way to use normal vibes bars, or you could commission a set of custom vibes bars in the right geometry to arrange chromatically (Nico vanderPlas can make you bars like these.) With either of these last two suggestions, I assume you would abbandon multiple rows in favor of two rows. Sounds like you still think multiple rows are a good idea. Do you mind my asking, why you think that is so?